I assume the copper wire was designed as a simple resistive switch? That will cause electrolysis and corrosion. There's an improved design that involves measuring capacitance, which also uses less power. I have a commercial sump pump monitor that works this way.
Yep, but in the end I was able to switch by monitoring the voltage generated by the water on the stainless rods, using a microcontroller. Worked great for a few years until I moved out. Haven't had a sump pump since. (good riddance)
